Fig. 2.

Histopathologic changes detected 7 dpi. B and C: black arrows indicate extensive drop out, degeneration, and necrosis of the ciliated epithelial cells; the open arrow indicates subserosal hemorrhage. E: black arrows indicate tubulointerstitial co;1;ngestion. F: black arrows indicate tubulointerstitial expansion and the open arrow indicates tubulointerstitial lymphocytic infiltrates. H and I: black arrows indicate hemorrhages; the open arrow indicates bronchial mucosal infiltration and congestion. K and L: black arrows indicate erythrocytes, inflammation, and exudates adhered to the mucous membrane surfaces; the open arrow indicates inflammatory infiltration of the lamina propria. A–F, J–O: scale bar =  50 μm; G–I, P–R: scale bar = 100 μm.